This invention relates to a data storage apparatus comprising a memory, and a user interface including a display and a keypad having a plurality of keys which can be pressed for entering data into and retrieving data from the memory.
A mobile telephone is an example of a data storage apparatus which is generally designed with only a limited number of keys. However, mobile telephones are generally provided with a telephone number index comprising a memory in which the user may store frequently used telephone numbers together with a respective alpha-tag (i.e. a text data `label`) such as, for example, the name of the subscriber. The user interface must therefore be capable of inputting not only numeric, but also alphabet characters.
In order to minimize the number of keys required it is common practice for at least some of the numeric keys which are normally used for dialing also to have other characters, specifically alphabet characters, associated therewith. For example, nine of the numeric keys (eg keys 1-9) may each have three other characters associated therewith. Thus only nine keys are needed to represent the 26 characters of the English alphabet and one further character, suitably a space character, making 27 characters in total, in addition to the nine numeric characters.
In a numeric data entry mode each of the numeric keys is pressed just once to enter the respective individual digits of a telephone number to be stored. When the full telephone number has been entered, an alphabetic data storage mode is initiated in which the three alphabet characters associated with a particular key may be selected respectively by pressing the key either once, twice or three times.
Similarly, in a data retrieval mode the individual characters of a name or label to be searched are entered by pressing the relevant keys once, twice or three times, as appropriate. When a match is found between a name stored in the memory and the sequence of characters being entered, the full name is shown on the display either simultaneously or intermittently with the associated telephone number also stored in the memory.
A drawback with this known arrangement is that many keystrokes are required for retrieving data from the memory and this can be time-consuming and irritating for the user. Specifically up to three keystrokes may be needed to enter a single character.